Helicopter



FIG. 1 is a right front perspective view of a helicopter showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a rear elevational view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken line showing of structural elements is included for the purpose of illustrating portions of the helicopter which form no part of the claimed design. 

CLAIM The ornamental design for a helicopter, as shown and described. 